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While upgrading my radiator and the cooling fan I decided to go ahead and change the thermostat. I pull the old one out and as I was about to insert the new one, find the bottom portion of the old thermostat still in the housing. Is this a normal thermostat failure?

My car has been overheating due to my fan malfunctioning which was determined by a shop, could this be caused by overheating? Should I be worried about any pieces running through the system? From what I understand by looking at the thermostat is that the bottom piece is actually stamped to the top piece, so nothing small is used to hold them that could have detached from the two. I flushed the cooling system out before reassembling everything, so far the car runs perfect "knock on wood".

While upgrading my radiator and the cooling fan I decided to go ahead and change the thermostat. I pull the old one out and as I was about to insert the new one, find the bottom portion of the old thermostat still in the housing. Is this a normal thermostat failure?

My car has been overheating due to my fan malfunctioning which was determined by a shop, could this be caused by overheating? Should I be worried about any pieces running through the system? From what I understand by looking at the thermostat is that the bottom piece is actually stamped to the top piece, so nothing small is used to hold them that could have detached from the two. I flushed the cooling system out before reassembling everything, so far the car runs perfect "knock on wood".

actually, that's two stage thermostat (what you pulled out.) the bottom separating like that is not normal which means yes, that was most likely causing the problem. They do normally have their own spring so the fact you didn't see it could mean it's somewhere in your cooling system. Not likely to cause an issue though....

Well my fan did quit working after 30 minutes of the car running at normal operating temperature. I am sure a thermostat in that shape was not fully operational, if at all. I am just glad I decided to go ahead and swap it out, otherwise I would have never known. Be as it may, the diagnosis by the shop that it was the cooling fan, was a good enough excuse for me to upgrade to a Mishimoto radiator and an SVT cooling fan. Ill just keep the thermostat as a possible cause of the problems to myself lol.

As far as the springs, both of them are still attached to the thermostat. And to be honest, I don't see any pieces that would be small enough to break off and go into the cooling system. I did however develop a bad rattling noise at higher rpms (a certain rpm range) some time ago, that sounded internal, which was going to get addressed after this problem was fixed. As of right now, after flushing the cooling system with water and reassembling everything, I have not heard the rattle again. Who knows, maybe something did get sucked up into the cooling system and got flushed out.

If your car was overheating.. shouldnt the shop have at least looked into the thermostat? I mean, its a super cheap part.. usually a common point of failure.. and takes 10 min for a shop to swap out. Seems odd. But who knows, maybe it failed recently.. you'll never know. What matters is the problem stays fixed.

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